At present, to reduce costs and energy, a base station often uses the multi-carrier structure, for example, multi-carrier WCDMA (Wideband Code Division Multiple Access, wideband code division multiple access), multi-carrier GERAN (GSM/EDGE Radio Access Network, GSM/EDGE radio access network), and Single RAN (single radio access network), where multiple carrier signals are amplified and sent through one channel of power amplifier and antenna. A drawback of this structure is that the PAPR (Peak to Average Power Ratio, peak to average power ratio) of a synthesized multi-carrier signal is high, which results in low efficiency of a power amplifier. Therefore, the PAPR needs to be suppressed in order to improve the efficiency of the power amplifier.
In the prior art, peak clipping is used to suppress the PAPR. That is, a standard cancellation signal is preset to detect the peak of the input signal, and adjust the peak according to information, such as the amplitude and phase of the peak value, and peak clipping threshold. The specific method can be as follows: adjusting the amplitude and phase of the standard cancellation signal so that the amplitude at the highest point of the standard cancellation signal is equal to the amplitude at the peak value of the input signal minus the peak clipping threshold but the phases are reverse. Then, the cancellation signal after adjustment is overlaid on the input signal to reduce the amplitude of the peak value to the peak clipping threshold, thereby reducing the PAPR.
When developing the present application, the inventor finds at least the following drawbacks of the prior art:
In existing systems such as GSM and GERAN, during frequency planning, the actual frequency reuse factor is often greater than 1, and neighboring cells use different carrier frequency points to avoid co-channel interference between neighboring cells. As shown in FIG. 1, the frequency point used by the cell in the middle of the figure is 0 (corresponding to the frequency group number A1 in FIG. 2). The first-layer neighboring cell frequency points of the cell are 4, 6, 7, 8, 9, and 10 (corresponding to frequency group numbers A2, C2, D2, A3, B3, and C3 in FIG. 2 respectively); the second-layer neighboring cell frequency points are 1, 2, 3, 5, and 11 (corresponding to frequency group numbers B1, C1, D1, B2, and D3 in FIG. 2 respectively). FIG. 2 is a 4×3 frequency reuse allocation table.
The existing peak clipping solution uses only the frequency in the current cell by default to bear peak clipping noises. Therefore, the entire performance of the system is not good enough.